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Tar Pit - outgoing emails
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Tar Pit - outgoing emails
21-11-2008 2:40 PM
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I thought Plusnet had a tar pit policy which drastically slowed outgoing emails if you sent them to a big mailing list.
Having read this by Bob over at TBB
Perhaps someone more knowledgeable than me could explain.
Having read this by Bob over at TBB
I have a question. This is equivalent to about 20 emails per second - so essentially the line must either have been saturated all weekend by sending individual emails or they got round the tar pit somehow.
Quote this particular issue <<hot mail blocking emails>> arose after one of our accounts got compromised by a spammer. They used the SMTP auth feature of the account to send in excess of 3 million spam emails over a single weekend before we realised and were able to stop it
Perhaps someone more knowledgeable than me could explain.
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Re: Tar Pit - outgoing emails
21-11-2008 3:03 PM
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If a spammer using a botnet sent the emails then it would take a lot more than 20 messages per second to saturate the bandwidth they have at their disposal. We do have tarpitting measures in place, however they're only effective to a certain degree and don't failsafe us against every eventuality.
Bob Pullen
Plusnet Product Team
If I've been helpful then please give thanks ⤵
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Re: Tar Pit - outgoing emails
21-11-2008 3:06 PM
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Doesn't the tar-pitting only apply to multiple recipients of a single email?
Will iron-port improve things when it takes over from relay.plus.net?
Will iron-port improve things when it takes over from relay.plus.net?
jelv (a.k.a Spoon Whittler) Why I have left Plusnet (warning: long post!) Broadband: Andrews & Arnold Home::1 (FTTC 80/20) Line rental: Pulse 8 Home Line Rental (£14.40/month) Mobile: iD mobile (£4/month) |
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Re: Tar Pit - outgoing emails
21-11-2008 3:16 PM
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Quote from: jelv Doesn't the tar-pitting only apply to multiple recipients of a single email?
There's a very top-level explanation on our website here. The following is from a *very* old discussion that I had internally when we altered the way that tarpitting worked. It's probably changed now and will be irrelevant anyway once we've moved to IronPort for outbound mail.
Quote from: Somebody assume 10 emails each to 40 recipients
Each email would have a 0.25 second delay increasing by a factor of 1.015 each time for 36 recipients.
Each email is therefore delayed by 11.82 seconds
After email 2 there would be a 0.5 second delay between each response increasing by 1.05 each time for 8 mails.
This adds in an additional delay of 4.77 seconds
This adds up to a total delay of
8 * 11.82 + 4.77 = 99.33 seconds.
Going on the second example and sending 20 emails to 20 recipients with exim would take:
18 * 4.48 + 14.07 = 94.76 seconds
If someone tried to send a single email to 400 recipients this would take 1hr 40 mins
Or if someone tried to send 400 emails to 1 recipient then this would take 19 hrs 25 mins (assuming that the SMTP connection was not closed between each mail)
I kind of lost interest with tarpitting after trying to get my head round that!
Quote Will iron-port improve things when it takes over from relay.plus.net
Yes, definitely.
Bob Pullen
Plusnet Product Team
If I've been helpful then please give thanks ⤵
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- Re: Tar Pit - outgoing emails